Air pollution caused by diesel engines can have harmful effect not only on the environment but also on human health. Research carried out around the world aims at reducing the emission of particles and harmful chemical compounds during the operation of diesel engines, an example of which is the use of fuel nanomodifiers. In the study presented, the effect of two fuel additives available in Poland, containing cerium dioxide and ferrocene nanoparticles was investigated. Additives were added to standard European diesel fuel to evaluate their influence on the emission of particulate matter and selected chemical compounds in exhaust gases from a vehicle equipped with a compression-ignition engine. Measurements were carried out using the New European Driving Cycle (NEDC), on a chassis dynamometer, simulating real road traffic conditions. The results showed a reduction of carbon monoxide, hydrocarbons and particulate matter (both in terms of mass and number of particles) in the exhaust gases, but also a 2-4% increase in nitrogen oxide emissions. The use of such nanomodifiers in diesel fuel seems to be a promising solution, especially for older passenger cars commonly used on the roads, which are not regulated by the latest emission standards.